There are many applications in which it is desirable or necessary to use an antenna to emit electromagnetic waves having a predefined directionality, i.e., having a predetermined directionality pattern, which is also referred to as a directional characteristic. It is advantageous in radar applications, for example, to emit electromagnetic waves having a certain directionality in order to be able to assign the electromagnetic waves reflected on an object and received to the position of the object.
In particular in radar applications, it is necessary to vary the direction in which the electromagnetic waves are emitted to be able to monitor a larger spatial area with the aid of the radar. Movable or swiveling antennas are used for this purpose, for example. Such antenna require a mechanical system which allows the antenna attached to the mechanical system to be suitably moved.
Furthermore, in conventional so-called phased array antennas, the antenna radiation pattern is electronically swivelable. Phased array antennas are made up of a plurality of antenna elements (array), which are supplied from a shared signal source. To swivel the antenna radiation pattern of such a phased array antenna, the individual transmitting elements of the phased array antenna are activated by a suitably phase-shifted signal. As a result, the individual emitted electromagnetic waves superimpose in the desired direction with a constructive interference and thus form, for example, a maximum or a minimum of radiated energy in the desired direction.
To individually set the phase and amplitude, such phased array antennas include a phase shifter and an attenuator for each of the transmitting elements. An antenna suitable for use in radar applications is described in German Patent Application No. DE 10 2010 040 793 A1, for example.